1. Field of the Invention
This invention relates to the mounting of electrical components on a printed circuit board.
2. Description of the Relevant Art
Light emitting diodes (LEDs) are well known. LEDs are commonly used in electrical circuits to indicate the status of a circuit, the change in status of a circuit, and/or to signal an alarm. In operation, LEDs are designed to xe2x80x9clight upxe2x80x9d when they pass current. Thus, LEDs are most commonly used on faceplates and other displays.
In many cases, the circuit or circuits of which the LED is a part, may be contained partially or wholly on a printed circuit board (PCB). Most PCBs typically include an electrically insulating substrate and a copper foil laid out or printed on one surface of the substrate according to a desired electronic circuit pattern. Resistors, capacitors, transistors, diodes and other electronic components are attached to the PCB according to the electronic circuit pattern.
In FIG. 1, a portion of a PCB 10 is shown, which has a component side 12, where components 14, such as ASICs, LEDS, memory chips, and generic processors, are mounted. The PCB 10 also has a solder side 16, where electrical connections to components 14 are made Typically, components are attached to PCBs by forming holes 18 through the substrate. At specific component attachment locations, leads or pins 20 from the components can be inserted through holes 18 from component side 12 of PCB 10, such that the component leads 20 project from solder side 16 of PCB 10. The projected portions of the component leads are soldered 22 to component-attaching lands 24 formed on solder side 16 of PCB 10.
When mounting components to the PCB it is desirable to keep the overall height profile of the PCB (with components) as thin as possible. This practice permits the greatest number of PCBs to be used together in the confines of a given card-based system, or to be used in miniaturized electronic devices. Typically, to insure a thin profile all components are mounted on a single side of the PCB. However, some components, such as the LED, take up valuable space on the component side of the PCB, which could be used for more valuable components. Accordingly, moving the LED to the solder side of the PCB, can significantly-improve the PCBs capacity. However, using the conventional component mounting method described above causes the LED to protrude out from the solder side of the PCB, significantly increasing the overall thickness of the PCB.
For these reasons, a need exists for a surface mountable LED, which may be mounted to the solder side of the PCB without significantly increasing the overall thickness profile of the PCB.
The present invention provides a surface mountable and low profile electrical component which can be electrically coupled to the solder side of a PCB, while other electrical components are mounted to a component side of the PCB. Advantageously, the electrical component is surface mounted to maintain a substantially low height profile.
As described in greater detail below, the surface mountable electrical component includes a mounting substrate having a diode or LED chip with electrical terminals. The LED chip is integrally mounted into a first side of the mounting substrate. Preferably, the LED chip extends out in a cantilevered arrangement from a first side of the mounting substrate. The terminals pass through the mounting substrate and extend out from an oppositely facing second side of the mounting substrate. The terminals can be electrically coupled to first and second electrical contacts, which provide an electrical pathway between the terminals and the PCB.
In operation, as the substrate is mounted to the PCB, the electrical contacts are made to intimately contact electrical conductors printed on the PCB, such that the electrical component becomes functional, which makes the LED chip operative.
There are many advantages to the present invention. For example, mounting space is created on the component side of the PCB for additional and potentially more valuable electrical components. As described in detail below, mounting the electrical component to the solder side of the PCB maintains a low thickness profile of the PCB.
Using the LED chip mounting technique of the present invention, a light source can be provided sufficiently thin, contributing to reduction in weight and size for portable apparatus or devices in which the electrical component is used.
Other uses, advantages, and variations of the present invention will be apparent to one of ordinary skill in the art upon reading this disclosure and accompanying drawings.